Systems and methods for damping building oscillations

ABSTRACT

A fluid transport system for actively damping oscillations of a structure affixed to a ground surface is disclosed. The system includes a pipe defining a flow path, a driver in fluid communication with the pipe and configured to provide a fluid flow through the pipe, and a controller. The controller is programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event.

BACKGROUND

Structures, such as buildings, bridges, and underwater superstructures, experience unique loading conditions during adverse weather conditions or seismic events. Such wind or seismic loading imposes constant, periodic, or irregular forces on the frame members of the structure. These forces displace at least a portion of the frame members. A structure may fail (i.e. plastically deform, collapse, etc.) where the displacement in the frame members exceeds a structural limit for the frame members, joints, and other components of the structure. A structure may utilize one or more damping systems to reduce the likelihood of failure.

Traditional methods for preventing a structure from failing include designed elasticity, passive damping systems, and viscous damping. Designed elasticity is often included as part of the initial design process of the structure and involves strategically positioning frame members to create an at least partially flexible structure. For a structure having designed elasticity, an input force may displace frame members without plastically deforming the structure. Passive damping systems similarly prevent a structure from failing but incorporate a passive system designed to reduce displacement of the frame members. By way of example, a building may include a weight positioned in an elevated position to counteract building sway. However, these systems are most efficiently installed during the initial design and construction of the structure thereby rendering them of reduced applicability to previously erected structures.

Other passive damping systems include damping devices (e.g., elastomeric isolators, isolation bearings, etc.) positioned within the structure or between the structure and a ground volume to reduce displacement of the structure. Viscous damping utilizes dampers positioned between frame members to dissipate energy and reduce displacement of the structure. However, these systems are most efficiently installed during the initial construction of the structure, and a structure may require numerous damping devices to reduce the displacement of frame members during adverse weather conditions or seismic events.

SUMMARY

One exemplary embodiment relates to a fluid transport system for actively damping oscillations of a structure affixed to a ground surface. The system includes a pipe defining a flow path, a driver in fluid communication with the pipe and configured to provide a fluid flow through the pipe, and a controller. The controller is programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event.

Another exemplary embodiment relates to an active damping system for a structure affixed to a ground surface. The system includes a driver and a fluid outlet, the fluid outlet configured to be coupled along an outer surface of the structure in an elevated location relative to the ground surface. The system also includes a connection pipe extending between the driver and the fluid outlet and defining a flow path and a controller. The controller is programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event.

Still another exemplary embodiment relates to a structure affixed to a ground surface. The structure includes a structural frame, a pipe coupled to the structural frame, the pipe defining a flow path, and a driver in fluid communication with the pipe and configured to provide a fluid flow through the pipe. The structure also includes a controller, and the controller is programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event.

Yet another exemplary embodiment relates to a method for actively damping a structure affixed to a ground surface by transferring fluid. The method includes providing a pipe, the pipe defining a flow path, providing a fluid flow through the pipe with a driver, and sending a fluid flow command signal with a controller in response to an event signal indicating an oscillation event.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an elevation view of a building.

FIG. 2 is an elevation view of a building having a damping device that includes a damping tube, according to an exemplary embodiment.

FIG. 3 is a side view of a building having a damping device that includes a damping tube, according to an exemplary embodiment.

FIG. 4 is an elevation view of a building having a damping device that includes a tube defining a circular flow path, according to an exemplary embodiment.

FIG. 5 is a side view of a building having a damping device that includes a tube defining a circular flow path, according to an exemplary embodiment.

FIG. 6 is an elevation view of a building having a damping device that includes a non-linear damping tube, according to an exemplary embodiment.

FIG. 7 is a side view of a building having a damping device that includes fluid storage devices, according to an exemplary embodiment.

FIG. 8 is an elevation view of a building having a damping device that includes a plurality of fluid outlets, according to an exemplary embodiment.

FIG. 9 is a side view of a building having a damping device including a fluid storage device and configured to change a mode of the building, according to an exemplary embodiment.

FIG. 10 is a side view of a building having a damping device including two fluid storage devices and configured to change a mode of the building, according to an exemplary embodiment.

FIG. 11 is a side view of a building having a damping device including two fluid storage devices and an elevated fluid flow device, according to an exemplary embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.

The damping systems described herein are intended to reduce the displacement of frame members within a structure during adverse weather conditions and seismic loading. Specifically, a system employing fluid active damping is intended to reduce the displacement of frame members within a structure by providing a force to counter wind and seismic loading. Damping systems may include lengths of pipe, tanks, or other structures that provide a fluid flow therethrough providing a countering force. In other embodiments, damping systems locate a fluid in different positions to change the fundamental period of the building. The fluid damping devices described herein are intended to offer various advantages relative to existing damping systems. Such advantages include, among others, the ability to deliver the fluid into numerous orientations within the structure, provide variable damping forces by changing the fluid flow rate, and utilize the fluid for another purpose (e.g., to provide water to operate fixtures within a building, to provide a fluid as part of a fire suppression system, etc.).

Further, the damping systems described herein may include a sensor (e.g., geophone, accelerometer, etc.) to facilitate real-time engagement of the damping system. Various control schemes may be included to further reduce the displacement of frame members within a structure during adverse weather conditions and seismic loading. Such schemes are intended to actively damp oscillations of a structure. Among other benefits, active fluid damping systems may be installed during the initial construction of a structure or retrofitted into existing structures.

Referring to the exemplary embodiment shown in FIG. 1, a structure, shown as building 10, includes a base portion 12 that interfaces with a ground volume 20. According to an exemplary embodiment, base portion 12 includes a plurality of structural members (e.g., pylons, pillars, etc.) extending into ground volume 20. In some embodiments, base portion 12 also includes a passive damping system, such as isolation bearings, elastomeric isolators, or other base-isolation systems. According to an alternative embodiment, building 10 does not include base portion 12 and instead includes another system that couples building 10 to ground volume 20.

According to an exemplary embodiment, building 10 includes an elevated portion 14 extending upwards from base portion 12. As shown in FIG. 1, elevated portion 14 includes a constant, rectangular cross section forming a prism. In other embodiments, elevated portion 14 includes a variable cross-sectional shape or forms another shape (e.g., trapezoidal, cylindrical, conical, irregular, etc.). It should be understood that various factors influence the shape of elevated portion 14. By way of example, aesthetics, structural design considerations, or a purpose of building 10 may produce an elevated portion 14 having a particular shape.

According to an exemplary embodiment, elevated portion 14 includes a frame, shown as super structure 16. In some embodiments, super structure 16 is designed to support the vertical weight loads of building 10 including the weight of floors, occupants, office spaces, structural beams, or still other elements. As shown in FIG. 1, super structure 16 is a three-dimensional network of support elements 18. The various support elements 18 may be arranged in a Type I arrangement having a semi-rigid or rigid fame, a Type II arrangement having a frame and shear trusses or a shear band and outrigger trusses, or a Type III arrangement forming an end channel framed tube with interior shear trusses. According to an alternative embodiment, super structure 16 includes a Type IV arrangement of support elements 18 having an exterior framed tube, a bundled framed tube, an exterior diagonalized tube, or a tubular core. It should be understood that building 10 may include still other combinations of support elements 18.

Referring next to the exemplary embodiment shown in FIGS. 2-3, a structure, shown as building 30, includes an elevated portion 32 extending from and affixed to a ground surface 40. According to an exemplary embodiment, building 30 includes a damping device, shown as fluid damping device 50. In some embodiments, fluid damping device 50 is provides damping forces to building 30 during an oscillation event (e.g., seismic activity, acceleration of the structure, displacement of at least a portion of the structure greater than a threshold level, etc.). As shown in FIG. 2, fluid damping device 50 includes a driver (i.e. flow generator, pump, pressure source), shown as flow device 60 and a tube (i.e. conduit, duct, pipe, etc.), shown as tube 70. Tube 70 may include a single pipe or several sections of pipe coupled together (e.g., welded, secured, fastened, etc.). According to an exemplary embodiment, tube 70 defines a flow path for a fluid. In some embodiments, flow device 60 is positioned at a ground level of building 30. In other embodiments, flow device 60 is located in an elevated position (e.g., on a second story, at the top story, between the ground level and top story, etc.) relative to ground surface 40.

In some embodiments, flow device 60 is in fluid communication with tube 70 and directs a fluid (e.g., water, hydraulic oil, a mixture including sand and water, etc.) through tube 70. According to an exemplary embodiment, flow device 60 is a centrifugal pump that delivers the fluid at a fluid flow rate (e.g., 100 gallons per minute, 100,000 gallons per minute, 300,000 gallons per minute, etc.). In some embodiments, flow device 60 includes an impeller that is rotated by an input device. Such an input device may be an electric motor, a fossil fuel powered engine, a liquid fueled rocket, a solid fueled rocket, compressed air, or another system. According to an alternative embodiment, flow device 60 is another type of pump. According to still another alternative embodiment, flow device 60 is a compressed fluid (e.g., air, nitrogen, etc.) that propels a fluid through tube 70. In still other alternative embodiments, flow device 60 is a tank that stores a compressed fluid. Once activated, such a flow device 60 releases the compressed fluid into tube 70.

As shown in FIGS. 2-3, tube 70 includes a linear section, shown as damping portion 72, and a section extending between flow device 60 and damping portion 72, shown as lift portion 74. According to an exemplary embodiment, damping portion 72 includes a first end and a second end. In some embodiments, a pressurized fluid flows from flow device 60, through lift portion 74, and into damping portion 72. As shown in FIGS. 2-3, the first end of damping portion 72 is positioned along a first side of building 30 and the second end of damping portion 72 is positioned along a second side of building 30. According to an exemplary embodiment, lift portion 74 extends between the first end of damping portion 72 and flow device 60. In alternative embodiments, tube 70 includes damping portion 72 and lift portion 74 having different lengths than those shown in FIGS. 2-3.

Referring to the exemplary embodiment shown in FIGS. 2-3, a fluid flows from an inlet, shown as inlet tube 62, to damping portion 72 through lift portion 74 upon activation of flow device 60. As shown in FIGS. 2-3, a fluid flowing from the first end to the second end of damping portion 72 interacts with an end cap 73. Such interaction imparts a force on end cap 73. In some embodiments, tube 70 includes auxiliary devices (e.g., check valves, vents, etc.) that facilitate such a fluid flow.

According to an exemplary embodiment, fluid damping device 50 reduces the oscillations of building 30 by delivering a fluid through damping portion 72. As shown in FIGS. 2-3, damping portion 72 is coupled to a frame of building 30, a portion of which is shown as super structure 80. According to an exemplary embodiment, a fluid flowing within damping portion 72 along a first direction will impart a damping force on super structure 80. A portion of the damping force is related to the product of the volumetric flow rate, the density, and the velocity of the fluid within damping portion 72. Such values for the fluid at the second end of damping portion 72 may be determined using the pressure of the fluid at an outlet of flow device 60, pressure losses within tube 70, and the lift head required to elevate the fluid from flow device 60, among other considerations.

Referring next to the exemplary embodiment shown in FIGS. 4-5, fluid damping device 50 includes tube 70 having damping portion 72, lift portion 74, a second linear portion, shown as damping portion 76, and a section extending between flow device 60 and the second end of damping portion 72, shown as lift portion 78. In some embodiments, flow device 60 flows a fluid through a fluid flow path defined by lift portion 74, damping portion 72, lift portion 78, and damping portion 76. Such a fluid flow may occur in the direction described (i.e. first upwards through lift portion 74) or in a reverse direction (i.e. first through damping portion 76). In some embodiments, the fluid is initially located within tube 70. Such a configuration may allow a portion of tube 70 to also serve as part of a fire suppression system of building 30 (e.g., tube 70 may include various outlets for sprinklers, etc.). In other embodiments, the flow device initially receives water from a fluid source and thereafter flow the fluid through tube 70.

According to an exemplary embodiment, fluid damping device 50 having lift portion 74, damping portion 72, lift portion 78, and damping portion 76 reduces the oscillations of building 30. As shown in FIGS. 4-5, damping portion 72 is coupled to super structure 80. According to the exemplary embodiment shown in FIG. 5, a fluid flowing from lift portion 74 to lift portion 78 through damping portion 72 imparts a damping force on super structure 80. In some embodiments, lift portion 78 is coupled to damping portion 72 with a coupler (e.g., bend, elbow, etc.). A fluid flowing through the coupler and changing directions (e.g., from a direction along damping portion 72 to a direction along lift portion 78) also imparts a damping force on super structure 80.

For an incompressible fluid and a constant area damping portion, a portion of the damping force is related to the product of the flow rate, fluid density, and change in velocity of the flowing fluid. Various factors impact the change in velocity of the flowing fluid including, among others, the surface roughness of the interior wall of damping portion 72 or the presence of paddles or interference members within damping portion 72. According to an exemplary embodiment, damping portion 72 includes an interior surface roughness designed to inhibit fluid flow (e.g., cast iron or another material and include an absolute roughness of 260 microns, concrete having a surface roughness of between 0.3 and 3 millimeters, etc.). In other embodiments, damping portion 72 includes at least one of an orifice and a flange to increase the change in velocity across damping portion 72.

While fluid flowing through damping portion 72 provides a damping force in a first direction, the fluid also provides a damping force in the opposite direction as it flows through damping portion 76. According to an exemplary embodiment, such a damping force is incorporated as part of a fluid damping strategy of fluid damping device 50. In other embodiments, the fluid damping strategy reduces damping forces due to fluid flowing through damping portion 76. Such a reduction may occur by reducing the surface roughness of the interior wall of damping portion 76, coupling damping portion 76 to a ground volume, or coupling damping portion 76 to building 30 with isolators (e.g., resilient members, dampers, etc.), among other alternatives.

Referring still to the exemplary embodiments shown in FIGS. 2-5, the damping portions are located in a plane orthogonal to a central axis of building 30 and extend laterally across a length of building 30. Such damping sections may include ends positioned at the same vertical location along building 30. In other embodiments, the damping sections are located in another plane that is not orthogonal to the central axis of building 30, include ends positioned at different vertical locations along building 30, or do not extend laterally across a length of building 30 (i.e. the damping portions are angled within various planes).

Referring next to the exemplary embodiment shown in FIG. 6, fluid damping device 50 includes flow device 60 and tube 70 having lift portion 74, lift portion 78, and a non-linear (i.e. curvilinear) portion, shown as non-linear damping portion 77. As noted above, fluid damping device 50 may provide damping forces to building 30 during an oscillation event. In some embodiments, non-linear damping portion 77 includes ends located along the same side of building 30. In other embodiments, tube 70 does not include lift portion 78 and non-linear damping portion 77 includes an end cap. In still other embodiments, non-linear damping portion 77 includes still other shapes. As shown in FIG. 6, non-linear damping portion 77 partially surrounds a central axis of building 30, and a fluid flowing through non-linear damping portion 77 applies a damping torque on super structure 80. From the foregoing, it should be understood that various shapes and configurations of pipes may be oriented to provide damping forces in various directions.

According to the exemplary embodiment shown in FIG. 7, a structure, shown as building 100 includes a base portion 102. As shown in FIG. 7, base portion 102 is coupled to a ground volume having a ground surface 104. According to an exemplary embodiment, building 100 includes an elevated portion 106. In some embodiments, building 100 includes a structural frame, a portion of which is shown as super structure 108.

As shown in FIG. 7, building 100 includes a damping device, shown as fluid damping device 110 positioned within elevated portion 106 and coupled to super structure 108. According to the exemplary embodiment shown in FIG. 7, building 100 includes fluid damping device 110 positioned at height “h” above ground surface 104. In other embodiments, building 100 includes a plurality of fluid damping devices 110 positioned at different elevations from ground surface 104.

Referring still to the exemplary embodiment shown in FIG. 7, fluid damping device 110 includes a first fluid storage device, shown as tank 112, and a second fluid storage device, shown as tank 114. Tank 112 and tank 114 may include several components arranged into a shell, the shell defining an inner volume and a fluid orifice. While shown in FIG. 7 as having a rectangular shape, tank 112 and tank 114 may have other suitable shapes (e.g., ovular, cylindrical, etc.). According to an exemplary embodiment, tank 112 and tank 114 are coupled to super structure 108 (e.g., with welding, a bolted connection, an adhesive, etc.). In some embodiments, forces applied to the inner surfaces of tank 112 and tank 114 are transferred to a portion of building 100 through super structure 108.

As shown in FIG. 7, tank 112 and tank 114 are positioned on opposing lateral sides of building 100. In other embodiments, tank 112 and tank 114 are located along the same lateral side of building 100. In still other embodiments, at least one of tank 112 and tank 114 are positioned along a centerline of building 100. According to an exemplary embodiment, tank 112 and tank 114 are positioned at the midpoint of each opposing side. Tank 112 and tank 114 may be positioned at ends of each opposing side (i.e. in opposing corners, etc.) or in still other positions. It should be understood from the foregoing that tanks 112 and 114 may be positioned in various positions of building 100.

As shown in FIG. 7, fluid damping device 110 includes a flow device 116 coupled to super structure 108 and disposed between tank 112 and tank 114. Such a position of flow device 116 may provide various advantages. By way of example, positioning flow device 116 between tank 112 and tank 114 reduces a delay (i.e. the time needed to deliver a fluid to tank 112 or tank 114), thereby improving a response time of fluid damping device 110.

Referring still to the exemplary embodiment shown in FIG. 7, fluid damping device 110 includes a first tube, shown as tube 118, and a second tube, shown as tube 119. As shown in FIG. 7, tube 118 extends between flow device 116 and tank 112, and tube 119 extends between flow device 116 and tank 114. Tube 118 and tube 119 may include ends disposed over the orifices of tank 112 and tank 114, respectively. Tube 118 and tube 119 may also include second ends, the second ends engaging a plurality of fluid ports defined by flow device 116. In some embodiments, tube 118 and tube 119 facilitate fluid communication between flow device 116, tank 112, and tank 114.

According to an exemplary embodiment, a fluid is disposed within the inner volume at least one of tank 112 and tank 114. According to an alternative embodiment, fluid damping device 110 includes an inlet pipe to couple flow device 116 with a fluid supply (e.g., retaining pond, container, etc.). Because of the fluid communication between flow device 116, tank 112, and tank 114, a fluid may be repositioned by flow device 116 into tank 112, into tank 114, emptied from both tank 112 and tank 114, or otherwise delivered through fluid damping device 110. According to an exemplary embodiment, the fluid is initially positioned within tank 112 (serving as the fluid supply), and flow device 116 delivers the fluid from tank 112 into tank 114. According to an alternative embodiment, the fluid is initially positioned within tank 114, and flow device 116 delivers the fluid from tank 114 into tank 112. It should also be understood that flow device 116 may selectively flow a fluid from a fluid supply into at least one of tank 112 and tank 114. Fluid damping device 110 may utilize the motion of the fluid flowing into tank 112 or tank 114 to provide a damping force to building 100 through super structure 108.

According to an alternative embodiment, fluid damping device 110 includes various fluid storage devices located in at least one of different elevations along elevated portion 106 and in different lateral positions relative to super structure 108. Such devices may include additional components (e.g., directional flow valves, check valves, etc.) to facilitate flow between the fluid storage devices. By way of example, fluid damping device 110 may include four fluid storage devices arranged as a first set positioned at a first elevation and a second set positioned at a second elevation. At least one flow device may deliver a fluid between the four fluid storage devices. The pairs of fluid storage devices may be positioned such that fluid flow between the first set of fluid storage devices provides a damping force along a first direction and fluid flow between the second set of fluid storage devices provides a damping force along a second direction. In some embodiments, the first direction is perpendicular to the second direction. Still other arrangements of fluid storage devices and piping may be provided to provide damping forces in still other directions, according to various alternative embodiments.

Referring next to the exemplary embodiment shown in FIG. 8, a structure, shown as building 140, includes a damping device, shown as fluid damping device 150. According to an exemplary embodiment, fluid damping device 150 provides damping forces to building 140 during an oscillation event. As shown in FIG. 8, fluid damping device 150 includes a flow device, shown as flow device 152. In some embodiments, flow device 152 delivers fluid from a fluid supply into other portions of fluid damping device 150. According to an exemplary embodiment, fluid damping device 150 includes a fluid inlet, shown as inlet tube 154, to couple flow device 152 with the fluid supply. As shown in FIG. 8, flow device 152 is coupled to building 140 at the elevation of a ground interface 142. In other embodiments, flow device 152 is coupled to building 140 at another elevation or positioned outside building 140, among other alternative configurations.

According to the exemplary embodiment shown in FIG. 8, fluid damping device 150 includes an elevating portion, shown as lift pipe 156. As shown in FIG. 8, lift pipe 156 includes a first end coupled to flow device 152 and an extended portion projecting upward along a first side of building 140. In other alternative embodiments, lift pipe 156 is positioned along a central portion of building 140.

As shown in FIG. 8, fluid damping device 150 includes a first subsystem, shown as first damping branch 160, and a second subsystem, shown as second damping branch 170. In some embodiments, building 140 defines an outer surface that interfaces with an exterior environment (e.g., surrounding air, surrounding water, etc.). According to an exemplary embodiment, the outer surface of building 140 defines a plurality of outlets to facilitate a fluid flow from an inner volume of building 140 to an exterior environment. As shown in FIG. 8, first damping branch 160 includes a plurality of fluid outlets, shown as nozzles 162, coupled along an outer surface of building 140. In some embodiments, nozzles 162 provide a fluid flow through the outlets of building 140.

Referring still to the exemplary embodiment shown in FIG. 8, first damping branch 160 includes a plurality of tubes (i.e. connection pipes), shown as coupling tubes 164, extending between nozzles 162 and a tube, shown as manifold tube 166. In some embodiments, second damping branch 170 includes a plurality of nozzles 172 coupled to manifold tube 176 with coupling tubes 174. As shown in FIG. 8, manifold tube 166 and manifold tube 176 each include an end coupled to lift pipe 156. Such a configuration is intended to couple nozzles 162 and nozzles 172 in fluid communication with flow device 152. In various alternative embodiments, other arrangements of pipes may couple nozzles 162 and nozzles 172 in fluid communication with flow device 152 (e.g., more or fewer lift pipes, fewer nozzles per damping branch, etc.).

Lift pipe 156, first damping branch 160, and second damping branch 170 define a plurality of flow paths between flow device 152, nozzles 162, and nozzles 172. According to an exemplary embodiment, flow device 152 delivers a fluid through lift pipe 156 and out of at least one of nozzles 162 and nozzles 172. In some embodiments, fluid is provided to nozzles 162 and nozzles 172 when flow device 152 is engaged (e.g., during an oscillation event). In other embodiments, fluid damping device 150 includes a valve to selectively deliver the fluid through nozzles 162 and nozzles 172 when flow device 152 is engaged. A controller selectively actuates the valve between a first position and a second position as part of a control scheme. In other embodiments, the valve is manually operable.

In still other embodiments, fluid damping device 150 includes a plurality of valves (e.g., a valve associated with each damping branch, a valve associated with each nozzle, etc.). In some embodiments, flow device 152 pressurizes the fluid (e.g., within a container, within lift pipe 156 and the damping branches, etc.). Upon actuation of the valves, the pressurized fluid is released through at least one nozzle. In some embodiments, flow device 152 continues to provide a fluid flow to the nozzles upon actuation of the valve such that the fluid flow from the nozzles is continuous. In other embodiments, flow device 152 pressurizes the fluid and thereafter disengages such that the fluid is directed from the nozzles in discrete amounts rather than as a continuous flow.

Referring still to the exemplary embodiment shown in FIG. 8, nozzles 162 and nozzles 172 direct a fluid into an exterior environment. According to an exemplary embodiment, nozzles 162 and nozzles 172 include housings having a cross sectional area that decreases in area such that the velocity of the fluid is increased as the fluid travels therethrough. It should be understood that such fluid is directed from building 140 with a force that is related to the diameter of the pipes, the flow rate, and the dimensions of the nozzle. In some embodiments, at least a portion of fluid damping device 150 is coupled to a frame member of building 140 to provide damping forces (e.g., reaction forces from nozzles 162 and nozzles 172) to building 140.

According to an exemplary embodiment, nozzles 162 and nozzles 172 each include a central axis. In some embodiments, the central axes of nozzles 162 and 172 are perpendicular to a central axis of building 140 (i.e. orthogonal to an outer surface of building 140). In other embodiments, at least a portion of the nozzles are arranged such that the central axes are angularly offset from an outer surface of building 140 to, by way of example, direct the fluid flow downward, upward, or to a side of building 140. In still other embodiments, fluid damping device 150 includes at least one moveable nozzle (i.e. a nozzle not having a fixed orientation relative to a structural frame of building 140 to provide variable damping forces). Regardless of orientation, fluid damping device 150 imparts damping forces from nozzles 162 and nozzles 172 to building 140 along an axis opposite the direction of fluid flow.

As shown in FIG. 8, nozzles 162 and nozzles 172 form a nozzle array along a face of building 140. While shown in FIG. 8 as positioned along a face of building 140, it should be understood that outlets may be defined along a single surface, along a plurality of surfaces, or along still other features of building 140. By way of example, building 140 may define two opposing outlets along a lateral direction and two opposing outlets along a longitudinal direction such that corresponding nozzles provide damping forces in various directions. As shown in FIG. 8, nozzles 162 and 172 form a two by three array. In various alternative embodiments, fluid damping device 150 includes nozzles arranged in a one dimensional array or includes nozzles arranged irregularly. In various alternative embodiments, a tube (e.g., coupling tube 164, coupling tube 174, etc.) may terminate into multiple nearby nozzles (e.g., nozzles 162, nozzles 172, etc.). Such nearby nozzles may be oriented in the same direction or oriented in different directions (e.g., perpendicular to each other). A valve may be used to control which of the nozzles is used to eject the fluid, and hence control the direction of the imparted damping force.

It should be understood that the damping device described herein may include any combination of flow devices, pipes, tanks, nozzles, or other components to provide damping forces during an oscillation event. Specifically, combinations of flow devices, pipes, tanks, nozzles, or other components may be incorporated in a configuration particularly suited for a structure. In some embodiments, the locations and orientations of the nozzles are selected based on knowledge of a selected natural vibrational mode of the structure (e.g., at sites of maximum modal deflection). The selected natural mode may be one whose modal frequency is similar to a potential seismic excitation frequency. The selected natural mode may be chosen based on numerical calculations of oscillations of the structure in response to anticipated seismic excitations. In some embodiments, the damping device includes specific components tailored for a particular loading condition (e.g., sharp seismic loading, dull or rolling seismic loading, wind loading, etc.) of a structure. By way of example, the damping device may include a fluid storage device positioned in an elevated location and a flow device that delivers a fluid from the fluid storage device out from a nozzle. Such a configuration may reduce the response time (i.e. the time between engaging the flow device and the structure experiencing damping forces), and such a reduction may be particularly relevant for sharp seismic loading capable of producing short duration yet large magnitude oscillations. In some embodiments, multiple flow devices are provided and situated at various locations within the damping device.

Referring next to the exemplary embodiment shown in FIGS. 9-10, a damping device, shown as fluid damping device 210, alters the natural vibration mode of a structure, shown as building 200. In some embodiments, altering the natural vibration mode of building 200 reduces the vibratory energy within building 200 during an oscillation event. As shown in FIG. 9, fluid damping device 210 includes a fluid flow device, shown as flow device 212, a first pipe, shown as tube 214, and a second pipe, shown as tube 216. According to an exemplary embodiment, tube 214 and tube 216 each include a first end coupled to flow device 212. In some embodiments, a second end of tube 214 interfaces with a fluid supply (e.g., a container, a retaining pond, etc.).

According to the exemplary embodiment shown in FIG. 9, a second end of tube 216 is coupled to a first fluid storage device, shown as tank 220. Tank 220 defines an inner storage volume that store a fluid, according to an exemplary embodiment. As shown in FIG. 9, tank 220 is coupled to a structural frame of building 200, a portion of which is shown as super structure 202 in an elevated position relative to a ground surface 204. As shown in FIG. 9, tube 214, flow device 212, and tube 216 define a flow path. According to an exemplary embodiment, flow device 212 delivers a fluid from tube 214 to tank 220 through tube 216. According to an alternative embodiment, flow device 212 delivers a fluid from tank 220 through tube 216 and tube 214 (i.e. flow device 212 delivers a fluid in either direction along the flow path). In other embodiments, flow device 212 selectively receives a fluid from tube 214, pressurizes the fluid, and thereafter provides the fluid to tank 220 through tube 216. Such a fluid damping device 210 may also include valves or other flow control devices to facilitate such operation. Valves may be actuated manually or by a controller as part of a fluid damping control scheme.

According to an exemplary embodiment, fluid damping device 210 delivers a fluid into tank 220 during an oscillation event to change the natural vibration mode of building 200. It should be understood that the natural vibration mode of structures may vary based on, among other factors, the materials used to build the structure, the design of the structure (i.e. the arrangement of structural components), and the distribution of weight within the structure. The weight of the fluid delivered into tank 220 may vary the distribution of weight within building 200 thereby altering the natural vibration mode and the frequency response of building 200 during an oscillation event. According to an alternative embodiment, fluid is delivered from a fluid storage device to alter the natural vibration mode of building 200, changing the mode's frequency and/or spatial shape.

According to the alternative embodiment shown in FIG. 10, fluid damping device 210 includes tank 220 and a second fluid storage device, shown as tank 222. In some embodiments, tank 222 is coupled to flow device 212 with tube 216 and super structure 202. As shown in FIG. 10, tank 220 is positioned at a first elevation of building 200 and tank 222 is positioned at a second, lower elevation of building 200. Such a configuration may allow flow device 212 to deliver a fluid into at least one of tank 220 and tank 222, the different positions of tank 220 and tank 222 allowing for fluid damping device 210 to variably alter the natural vibration mode of building 200. In some embodiments, valves are positioned within the flow path to selectively allow a fluid flow to or from at least one of tank 220 and tank 222. According to an alternative embodiment, a fluid damping device includes multiple flow devices, more or fewer fluid storage devices, or the fluid storage devices are otherwise positioned.

According to still another alternative embodiment shown in FIG. 11, flow device 212 of fluid damping device 210 is coupled to building 200 in an elevated position. As shown in FIG. 11, flow device 212 is positioned within building 200 between tank 220 and tank 222. Such an elevated position of flow device 212 may reduce a response time of fluid damping device 210, reduce the need for additional piping, or provide still other benefits. According to an exemplary embodiment, pipes, shown as tubes 218, couple tank 220 and tank 222 to flow device 212. According to an exemplary embodiment, a fluid is disposed within at least one of tank 220 and tank 222, and flow device 212 delivers the fluid from at least one of tank 220 and tank 222 (e.g., from one fluid storage device into the other fluid storage device) during an oscillation event to change the natural frequency mode of building 200. In some embodiments, fluid damping device 210 includes a pipe coupling flow device 212 with a fluid supply (e.g., container, retaining pond, etc.) to, by way of example, facilitate the initial filling of tank 220 or tank 222, facilitate the emptying of tank 220 or tank 222, or otherwise engage with other components of fluid damping device 210 as part of a damping control scheme.

According to an exemplary embodiment, a fluid damping device includes a controller and a fluid flow device. The controller interfaces with the fluid flow device. The controller may send or receive command signals to engage or disengage the fluid flow device, change the direction of the fluid flow from the fluid flow device, or change the rate that the fluid is discharged from the fluid flow device, among other alternatives. In some embodiments, the controller sends a command signal after receiving an event signal indicating an oscillation event. By way of example, a sensor (e.g., geophone, accelerometer) that detects seismic activity, acceleration, structural stress or strain, structural deflection, fluid mass, volume, or forces, or another phenomena may send the event signal. In some embodiments, the sensor is coupled to a portion of the structure (e.g., the top of a building, a middle point of a bridge, other suitable locations, etc.). In some embodiments, accelerations can be measured along multiple directions, or in different sites. Differential accelerations between different directions or locations may be used to measure modal excitations. Structural deflections may be derived (e.g., from double integration of accelerations) or directly measured relative to external references (e.g., with a global positioning system, a differential global positioning system, interferometers, or other metrology tools), according to various alternative embodiments. In other embodiments, the sensor interacts remotely with a fluid damping device (e.g., sensors positioned at established geographic seismology facilities, etc.).

According to an exemplary embodiment, the controller includes a module coupled to the sensor, and the sensor provides a sensor signal to the module. Such a module processes the sensor signal and determines whether an oscillation event may occur, is occurring, or has occurred. In some embodiments, the module includes various parameters (e.g., a threshold acceleration or displacement, etc.), the parameters allowing the module to identify an oscillation event and provide an event signal. According to an exemplary embodiment, the module provides the event signal to the controller, which provides a command signal to a component of the fluid damping device.

According to an exemplary embodiment, the controller includes a processing circuit to implement a control strategy that damps oscillations within a structure. In some embodiments, the control strategy is computed in real-time based on numerical simulations of the oscillation. In other embodiments, the control strategy is selected from one or more pre-derived control strategies. During an oscillation event, such as an earthquake, a building may sway significantly. Failure to implement a control strategy may impart excessive stresses within the structure. Such excessive stresses may allow a building to experience the first, second, or third failure modes.

In some embodiments, the controller implements a control strategy that incorporates several damping techniques. It should be understood that some earthquakes exhibit loading that provides the largest displacement within the first minute and the largest peak loading within the first half of the seismic event. According to an exemplary embodiment, a sensor coupled to a building senses at least one of a building oscillation and a building displacement. In some embodiments, a controller interprets the sensor data, determines whether the data indicates an oscillation event based on a threshold acceleration (e.g., 1.0 meters per second squared) or a threshold displacement (e.g., 0.5 meters), and interfaces with a fluid damping device (e.g., turn on a fluid flow device, engage a valve to facilitate fluid flow, etc.) to provide damping forces. In other embodiments, the controller engages the damping device to apply predetermined damping forces after receiving various features describing an oscillation event (e.g., location, magnitude, and starting time of an earthquake).

According to an exemplary embodiment, the fluid damping device provides damping forces to particular locations of the building. The distribution of damping forces may be related to the loading imparted during the oscillation event. By way of example, the upper portion of a building experiencing large loading due to wind may sway more than other portions, and a damping force applied to an elevated position of the building may reduce at least one of the displacement and acceleration of the building. According to an exemplary embodiment, the controller operates with an initial damping strategy of applying a single damping force, a plurality of damping forces concurrently, or a plurality of damping forces in a pattern designed to damp structure oscillations (e.g., apply a force to different portions of the building, apply a damping force first using damping pipes or nozzles and then using tanks, etc.), among other potential initial damping strategies.

In some embodiments, the fluid damping device provides only an initial damping force. According to an exemplary embodiment, the fluid damping device provides an initial damping force or changes the natural building mode, monitors a response by the structure, and provides additional damping forces or again change the natural building mode. The fluid damping device may continue this iterative process until a condition is satisfied (e.g., the building no longer experiences loading from the oscillation event, the building no longer accelerates or is displaced, etc.).

As described above, a fluid damping device generates a damping force by delivering a fluid at least one of through a damping pipe, into a fluid storage device, and through a nozzle. In some embodiments, the fluid damping device interfaces with still other damping devices (e.g., passive dampers, fluid viscous dampers, etc.) to operate as part of a coordinated damping system. According to an exemplary embodiment, the building includes a fluid damping system capable of providing damping forces in various directions to, by way of example, reduce oscillations due to loading in various directions.

Additional vibratory energy may be imparted into the structure where loading during an oscillation event excites a natural vibration mode of the structure. A fluid damping device damps the additional vibratory energy that may otherwise damage the structure. According to an exemplary embodiment, the fluid damping device changes the natural vibration mode of the structure to a mode that is offset (e.g., out of phase with, having a different phase angle, etc.) from the frequency of the loading. Such a change in the vibration mode may be effective in various conditions (e.g., where the input from the oscillation event is in a narrow frequency band).

According to an exemplary embodiment, the controller first reduces oscillation due to loading by applying a damping force and thereafter engages a fluid flow device to deliver a fluid (e.g., into or from a fluid storage device) to change the natural vibration mode of the structure. According to an alternative embodiment, the controller interfaces with the damping device to provide only damping forces, only change the natural vibration mode, first change the natural vibration mode and thereafter apply damping forces, or employ still another strategy. While an illustrative control strategy has been described, it should be understood that a fluid damping device may include a particular control strategy for a specific structure. Further, fluid damping devices may be employed in buildings, bridges, or other structures to damp loading due to earthquakes, wind, or other inputs. Such buildings, bridges, or other structures may be affixed to a ground surface (e.g., directly coupled, coupled with pylons, coupled with hydraulic or polymeric isolators, etc.).

It is important to note that the construction and arrangement of the elements of the systems and methods as shown in the exemplary embodiments are illustrative only. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements. It should be noted that the elements and/or assemblies of the enclosure may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Additionally, in the subject description, the word “exemplary” is used to mean serving as an example, instance or illustration. Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word exemplary is intended to present concepts in a concrete manner. Accordingly, all such modifications are intended to be included within the scope of the present inventions. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the preferred and other exemplary embodiments without departing from scope of the present disclosure or from the spirit of the appended claims.

The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data, which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

Although the figures may show a specific order of method steps, the order of the steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps. 

1. A fluid transport system for actively damping oscillations of a structure affixed to a ground surface, comprising: a pipe defining a flow path; a driver in fluid communication with the pipe and configured to provide a fluid flow through the pipe; and a controller programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event. 2-20. (canceled)
 21. The system of claim 1, further comprising a sensor operatively coupled to the controller.
 22. The system of claim 21, further comprising a module, wherein the sensor is configured to provide a sensor signal to the module.
 23. The system of claim 22, wherein the module provides the event signal to the controller when the sensor signal exceeds a threshold level. 24-54. (canceled)
 55. The system of claim 1, further comprising a first tank in fluid communication with the driver.
 56. The system of claim 55, wherein the first tank is in fluid communication with the pipe. 57-62. (canceled)
 63. The system of claim 55, wherein the first tank is coupled to the structure.
 64. (canceled)
 65. The system of claim 63, further comprising a second tank in fluid communication with the driver.
 66. The system of claim 65, wherein the second tank is in fluid communication with the pipe.
 67. The system of claim 66, wherein the first tank is in fluid communication with the second tank via the pipe. 68-81. (canceled)
 82. An active damping system for a structure affixed to a ground surface, comprising: a driver; a fluid outlet configured to be coupled along an outer surface of the structure in an elevated location relative to the ground surface; a connection pipe coupled to the driver and the fluid outlet and defining a flow path; and a controller programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event.
 83. The system of claim 82, wherein the controller is configured to control the driver using the fluid flow command signal. 84-85. (canceled)
 86. The system of claim 82, further comprising a valve positioned within the flow path. 87-93. (canceled)
 94. The system of claim 82, further comprising a second fluid outlet, the second fluid outlet configured to be coupled along the outer surface of the structure. 95-108. (canceled)
 109. The system of claim 94, further comprising a second connection pipe coupled to the driver and the second fluid outlet, the second connection pipe defining a second flow path.
 110. The system of claim 109, further comprising a valve, wherein the controller is programmed to selectively actuate the valve between a first position and a second position. 111-113. (canceled)
 114. The system of claim 110, further comprising a pressurized container configured to store a pressurized fluid.
 115. (canceled)
 116. The system of claim 114, wherein the valve directs a fluid flow from the pressurized container to the first fluid outlet when in the first position.
 117. The system of claim 114, wherein the valve directs a fluid flow from the pressurized container to the second fluid outlet when in the second position.
 118. The system of claim 109, further comprising a first valve coupled along the first flow path and a second valve coupled along the second flow path.
 119. The system of claim 118, wherein the fluid flow command signal is configured to selectively actuate the first valve and the second valve between a first position and a second position. 120-195. (canceled)
 196. A structure affixed to a ground surface, comprising: a structural frame; a pipe coupled to the structural frame, the pipe defining a flow path; a driver in fluid communication with the pipe and configured to provide a fluid flow through the pipe; and a controller programmed to send a fluid flow command signal in response to an event signal indicating an oscillation event. 197-221. (canceled)
 222. The structure of claim 196, further comprising a fluid outlet coupled along an outer surface of the structure in an elevated location relative to the ground surface, wherein the pipe extends between the driver and the fluid outlet and defines a flow path.
 223. The structure of claim 222, further comprising a second fluid outlet coupled along the outer surface of the structure.
 224. The structure of claim 223, wherein the first fluid outlet and the second fluid outlet are positioned at different vertical locations of the structure. 225-230. (canceled)
 231. The structure of claim 223, wherein the first fluid outlet defines a first fluid flow direction and the second fluid outlet defines a second fluid flow direction.
 232. (canceled)
 233. The structure of claim 231, wherein the first fluid flow direction opposes the second fluid flow direction. 234-262. (canceled)
 263. The structure of claim 196, further comprising a first tank in fluid communication with the driver. 264-270. (canceled)
 271. The structure of claim 263, wherein the first tank is coupled to the structural frame. 272-273. (canceled)
 274. The structure of claim 271, further comprising a second tank in fluid communication with the driver. 275-276. (canceled)
 277. The structure of claim 274, wherein the first tank is positioned at a first vertical location of the structure and the second tank is positioned at a second vertical location of the structure.
 278. The structure of claim 274, wherein the second tank is offset from a centerline of the structure.
 279. The structure of claim 278, wherein the first tank is positioned on a first side of the structure and the second tank is positioned on a second side of the structure. 280-291. (canceled)
 292. The structure of claim 196, wherein the pipe comprises a damping pipe.
 293. The structure of claim 292, wherein the damping pipe includes a linear section positioned along a first axis of the structure. 294-422. (canceled) 